"No free man shall ever be debarred the use of arms. The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government." Thomas Jefferson, proposed Virginia constitution, June 1776. Thomas Jefferson Papers, 334 (C. J. Boyd, Ed., 1950)
"Laws that forbid the carrying of arms disarm only those who are neither inclined nor determined to commit crimes. Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man." Thomas Jefferson, quoting 18th century criminologist Cesare Beccaria in "On Crimes and Punishment", 1764, pp 87-88.
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms." Samuel Adams, During the Massachusetts U.S. Constitution ratification convention, 1788
"Arms in the hands of citizens may be used at the individual discretion, in private self-defense." John Adams, A Defense of the Constitutions of Government of the United States of America, 1787-88
"I ask sir, what is the militia? It is the whole people. To disarm the people is the best and most effectual way to enslave them." George Mason, during Virginia's ratification convention, June 4, 1788 (From J. Elliott, Debates in the General State Conventions 425 (3rd ed. 1937).
"The right of the people to keep and bear arms shall not be infringed. A well regulated militia, composed of the body of people, trained in arms, is the best and most natural defense of a free country." James Madison, I Annuals of Congress 434 (June 8, 1789)
That was almost word for word the phrasing of the 2nd Amendment, which makes our 4th President essentially the author of said amendment. But he also had this further to say in "The Federalist", in which he DEFINES what it means:
"The Constitution preserves the advantage of being armed which Americans possess over the people of almost every other nation where the governments are afraid to trust the people with arms." James Madison, The Federalist No. 46
That last one was straight from the author of the amendment himself....